METHOD OF HEAT TREATMENT OF STEEL Russian patent published in 2024 - IPC C21D6/04 C21D1/56 C21D1/18 

FIELD: various technological processes.

SUBSTANCE: invention relates to heat treatment of steel parts. Method of heat treatment of steel part includes heating for hardening, holding at hardening temperature, subsequent cooling and tempering, wherein duration of heating for hardening is determined by calculation from condition of 2 minutes per each millimetre of the part cross-section thickness, the part holding time in the furnace is determined by calculation based on condition of 1 min per each millimetre of the part cross-section thickness, cooling is carried out in a hardening medium until the part reaches a temperature of minus 15 °C to minus 13 °C, duration of part staying in hardening medium is from 15 to 20 s, after which the part is cold treated in the medium of isopropyl alcohol at a temperature of minus 40 °C for 12 hours, heating in air to temperature of normal conditions, low tempering at temperature of 120 °C for 40 minutes, and cooling in air, wherein the hardening medium used is water with the addition of sodium lactate or an aqueous solution of calcium chloride, or an aqueous solution of sodium chloride, or an aqueous solution and caustic soda.

EFFECT: providing the specified high hardness of the part from steel without hardening cracks in the part.

1 cl, 2 tbl